The present invention relates generally to the field of optics
There are many instances wherein it is desirable that the frequency of a laser be changed to another frequency, often a harmonic of the frequency of the laser. For example, many frequencies, such as, for example, visible frequencies, are relatively hard to produce using inexpensive lasers. Thus, to obtain such a visible frequency, an infrared laser beam is directed onto a material that has non-linear optical properties. When the laser beam arrives into the material, harmonics are generated so that the frequency of the laser is converted to a converted beam having an higher frequency.
One problem that occurs in this type of device is that the phase constant of the converted beam has to be the same as the phase constant of the incident beam throughout the material so that conversion is efficient. If the material is relatively long, so as to allow a relatively large conversion, this condition may be hard to achieve, as it requires a relatively narrow bandwidth incident laser light.
Another problem that occurs in many such devices is that these devices often include relatively large optical elements, such as lenses, which therefore prevent manufacturing relatively compact light sources.
Furthermore, there is often a need to control the temperature of the elements included in a wavelength conversion device. Temperature is typically controlled using a plurality of temperature controllers, each coupled to a different component. The use of many temperature controllers increases the size of the device and reduces its energy efficiency.
Accordingly, there exists a need for an improved light source.
It is a general object of the present invention to provide such a light source.